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Hydrogen peroxide as an electron acceptor for mitochondrial respiration in the yeast Hansenula polymorpha
Author(s) -
Verduyn Cornelis,
Van Wijngaarden Connie J.,
Alexander Scheffers W.,
Van Dijken Johannes P.
Publication year - 1991
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.320070207
Subject(s) - electron acceptor , chemostat , hydrogen peroxide , respiratory chain , biology , cytochrome c peroxidase , biochemistry , catalase , electron donor , yeast , cytochrome c , enzyme , cytochrome , peroxidase , oxygen , nad+ kinase , photochemistry , mitochondrion , chemistry , catalysis , organic chemistry , bacteria , genetics
Chemostat cultures of a catalase‐negative mutant of Hansenula polymorpha CBS 4732 were able to decompose hydrogen peroxide at a high rate. This was apparent from experiments in which yeast was grown under carbon limitation in chemostat culture on mixtures of glucose and H 2 O 2 . The enzyme responsible for H 2 O 2 degradation is probably the mitochondrial enzyme cytochrome c peroxidase (CCP), which was present at very high activities. This enzyme was partially purified and shown to be specific for reduced cytochrome c as an electron donor; no reaction was observed with NAD(P)H. Thus, reducing equivalents for H 2 O 2 degradation by CCP must be provided by the respiratory chain. That H 2 O 2 can act as an electron acceptor for reducing equivalents could be confirmed with experiments in which cells were incubated with ethanol and H 2 O 2 in the absence of oxygen. This resulted in oxidation of ethanol to equimolar amounts of acetate. Energetic aspects of mitochondrial H 2 O 2 decomposition via CCP and the physiological function of CCP in yeasts are discussed.